Linux From Scratch (LFS) is a project that provides you with
step-by-step instructions for building your own GNU/Linux OS
from source code. URL: http://www.linuxfromscratch.org/
One Day One Command
ltrace — Library call TRACEr
ltrace is a program that simply runs the specified command until it
exits and intercepts & records the library/system calls, which are
called by the executed process, and the signals, which are received by
that process. It can used study the internal flow of a program.
$ ltrace sleep 1 — Trace all Lib call of ‘sleep’ command.
$ ltrace ls — Trace all Lib call of ‘ls’ command.
$ ltrace -d sleep 1 — Print more detailed info.
$ ltrace -i sleep 1 — Print the value of the Instruction Pointer at
every lib call.
$ ltrace -S sleep 1 — Show System Call trace also.
$ ltrace -S -L sleep 1 — Show only System calls.
$ ltrace -r sleep 1 — Print a relative time-stamp with each line of
$ ltrace -t sleep 1 — Prefix each line of the trace with the time of
$ ltrace -o file sleep 1 — Redirect the output to a file.
$ sleep 60 & — Dummy background Job.
$ ltrace -p 1234 — Attach to the process with the PID 1234 (use dummy
job’s Pid) and trace.
$ ltrace -n 3 sleep 1 — Indent each new nested call by 3 Spaces.
Read: man ltrace